package LinkList;

public class LinkedList {
    static class ListNode{
        public  int val;
        public ListNode prev;
        public  ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public  ListNode head;
    public  ListNode last;
    //头插法
    public void addFirst(int data){
        ListNode cur = head;
        ListNode node = new ListNode(data);
        if (head==null){
            head = last = node;
        }else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode cur = head;
        ListNode node = new ListNode(data);
        if (head==null){
            head = last = node;
        }else {
            last.next = node;
            node.prev =  last;
            last = last.next;
        }

    }
    //任意位置插入,第一个数据节点为0号下标
    public boolean addIndex(int index,int data){
        ListNode cur =head;
        ListNode node = new ListNode(data);
        int len = size();
        if (index<0||index>len){
            return false;
        }
        if (index==0){
            addFirst(data);
            return true;
        }
        if (index==len){
            addLast(data);
        }
        while (index !=0){
            cur = cur.next;
            index--;
        }
        node.next = cur;
        cur.next.prev = node;
        node.prev = cur.prev;
        cur.prev = node;
        return false;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while (cur !=null){
            if (cur.val==key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while (cur !=null){
            if (cur.val==key){
                //开始删除
                if (cur==head){
                    head = head.next;
                    if(head !=null){
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next ==null){
                        last = last.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = head;
        while (cur !=null){
            if (cur.val==key){
                //开始删除
                if (cur==head){
                    head = head.next;
                    if(head !=null){
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next ==null){
                        last = last.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }
    //得到单链表的长度
    public int size(){
        int count  =0;
        ListNode cur = head;
        while (cur !=null){
            count++;
            cur = cur.next;
        }
        return count;
    }
    public void display(){
        ListNode cur = head;
        while (cur !=null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }
    public void clear(){
        ListNode cur = head;
        while (cur !=null){
            ListNode curN = cur.next;
            cur.prev = null;
            cur.next = null;
            cur =curN;
        }
        head = last = null;
    }
}
